MCM-41分子筛负载Pd/La0.8Ce0.2MnO3低温催化燃烧甲苯实验研究

Experimental study on low temperature catalytic combustion of toluene by Pd/La0.8Ce0.2MnO3 supported on MCM-41

关键词:  挥发性有机物  钙钛矿  贵金属  低温催化燃烧  分子筛

Key words:  VOCs  perovskite  noble metal  catalytic combustion  molecular sieve

摘要:

以贵金属改性的钙钛矿为活性组分,采用等体积浸渍法制备Pd/La0.8Ce0.2MnO₃/MCM-41催化剂,以甲苯为模型污染物进行催化燃烧实验,考察焙烧温度、负载量对催化反应的影响,并通过XRD、BET、SEM等手段对催化剂进行表征。结果表明:Pd/La0.8Ce0.2MnO₃/MCM-41催化剂具有完整的钙钛矿型结构,Pd在钙钛矿型氧化物上得到高度的分散,同时MCM-41也发挥了很好的载体效应,有利于催化剂活性的发挥;La0.8Ce0.2MnO₃负载量为20％、焙烧温度在750 ℃,起燃温度和完全转化温度分别为203和283 ℃;在加入0.05％ Pd后,La0.8Ce0.2MnO₃/MCM-41催化活性显著增强,甲苯完全转化温度仅为235 ℃;催化剂表面活性组分具有高分散性,活性组分颗粒粒径均一,分散均匀。

Abstract:

Pd/La0.8Ce0.2MnO₃/MCM-41 catalyst was prepared by isovolumetric impregnation method using the noble metal modified perovskite as the active component. The catalytic combustion mechanism was investigated using toluene as the model pollutant, in which the influence of calcination temperature and loading capacity on the catalytic reaction was considered. Also, the catalyst was characterized by Brunauer-Emmett-Teller (BET),X-ray diffraction (XRD) and scanning electron microscope (SEM). It is found that the Pd/La0.8Ce0.2MnO₃/MCM-41 possesses an integrated perovskite structure, on which the Pd has been dispersed evenly, and the catalyst performs good activity. The light-off temperature and the complete combustion temperature of toluene is only 20 3 ℃ and 283 ℃ respectively when the loading capacity of La0.8Ce0.2MnO₃ is 20％ under the calcination temperature of 750 ℃. At the same scenario, the complete combustion temperature of toluene is only 235 ℃ after the modification of adding 0.05％ Pd, which is attributed to the significant enhanced catalytic activity of La0.8Ce0.2MnO₃/MCM-41. Also, the active components on the catalyst show good dispersity with even particle size.